Melanoma of the female genitalia continues to have an unfavorable prognosis, particularly thicker lesions that are not amenable to surgery, according to data from one of the largest clinical series ever reported.

Half of the 85 patients died within 5 years and just 30% remained alive at 10 years. Diagnosed between 1970 and 2009, the lesions affected women spanning the age range from teenagers to nonagenarians.

Thinner lesions and wide-margin surgical resection predicted better survival, as reported at the American Academy of Dermatology meeting in San Diego.

"Like any melanoma ulcer on the body, when it's caught earlier, we have a much greater opportunity to provide a cure than when things are diagnosed later," Kelly Nelson, MD, of Duke University, told MedPage Today.

"What a lot of women I have seen after diagnosis have told me is that they weren't even aware [the lesion] was there until it became painful or began to bleed," she added. "That relates back to encouraging women to be aware of their bodies and to include examination of that area when they look at the rest of their skin on a monthly basis."

Melanoma of the female genitalia is an uncommon malignancy that historically has a poor prognosis, associated with a mean 5-year survival of 36% and a range of 8% to 55%. Factors influencing prognosis have remained unclear, a circumstance Nelson and colleagues sought to address in a retrospective review of medical records.

The investigators limited their search to women with a diagnosis of primary melanoma of the genitalia. They selected 85 patients for closer evaluation.

Whites accounted for 78 of the patients (92%), whose age ranged from 19 to 92. Median follow-up was 8.8 years, and 60% of the patients had died at last follow-up. The cohort had a 1-year survival of 81%.

By log rank analysis, survival had inverse associations with lesion thickness, extent of nodal involvement, and use of systemic therapy. Wide local excision was associated with improved survival.

Information in many cases was sketchy at best, forcing investigators to use whatever clinical data they could locate.

"In about half of the cases, the anatomic site was not specified," said Nelson. "That makes it kind of hard to get a lot of detail."

The relatively scant literature on the topic has shown that the location of genital melanoma in women runs the gamut from primarily external to primarily internal, including the cervix.

Tumor thickness, available for 51 patients, averaged 3.2 mm, and the median value was 2.3 mm.

Histopathology findings were available for 36 patients. Review by an experienced dermatopathologist showed that superficial spreading was the predominant subtype, along with some cases of nodular and acral lentiginous subtypes.

In 31 of 36 cases, lesions arose de novo with no evidence of pre-existing nevi. Additionally, 12 cases were amelanotic, and 15 patients had atypical melanocytic hyperplasia adjacent to the primary melanoma.

Like most other aspects of melanoma of the female genitalia, information about histology, aggressiveness, and other lesions characteristics remains limited. Recent research has shown that multiple molecular subtypes fall under the umbrella of melanoma.

"We're starting to see some associations between the type of tumor and its location," said Nelson. "For example, tumors that arise in a woman's private area tend to be molecularly different from tumors that arise on chronically sun-damaged skin of an older person."

Some signs have pointed to beginning of an emergence of melanoma of the female genitalia from its relative obscurity. In particular, more patients seem to be diagnosed at earlier stages than in the past.

"I think that's a combination of patients becoming more comfortable with examining their bodies and gynecologists or primary care physicians becoming more attuned to looking for the lesions," said Nelson.

Gynecologists have the greatest opportunity to detect the lesions at the earliest possible stage. A key to earlier detection is better identification of pigmented lesions characteristic of melanoma as compared with pink lesions that are often associated with squamous cell cancers, she added.